U.S. patent number 11,408,264 [Application Number 16/952,704] was granted by the patent office on 2022-08-09 for volumetric fracturing method of temporarily plugging and diverting through functional slick water with oil displacement agent injected simultaneously.
This patent grant is currently assigned to JINGZHOU MODERN PETROLEUM TECHNOLOGY DEVELOPMENT CO. LTD, YANGTZE UNIVERSITY. The grantee listed for this patent is Jingzhou Modern Petroleum Technology Development Co. LTD, YANGTZE UNIVERSITY. Invention is credited to Fei Ding, Pingtian Fan, Rui Li, Wenming Shu, Baocheng Wu, Wenjie Xia, Weichu Yu, Lei Zhang, Ying Zhang, Hui Zhao.
United States Patent |
11,408,264 |
Yu , et al. |
August 9, 2022 |
Volumetric fracturing method of temporarily plugging and diverting
through functional slick water with oil displacement agent injected
simultaneously
Abstract
Disclosed is a method for determining three-dimensional in-situ
stress based on displacement measurement of borehole wall,
including the following steps: pumping the prefluid and the
sand-carrying fluid into the target interval, and injecting the
biological oil displacement agent into the target interval in
sequence; pumping temporary plugging agent into the target layer to
implement crack plugging diverting; pumping the sand-carrying
liquid into the target interval, and injecting the biological oil
displacement agent into the target interval. The beneficial effect
of the technical scheme proposed in this disclosure is: by
injecting oil displacement agent to fracturing fluid, the temporary
plugging diverting fracturing is integrated constructed with
enhanced oil recovery, at the same time, it can overcome the
incomplete removal of temporary plugging agent and the water lock
effect of fracturing fluid caused by diverting fracturing.
Inventors: |
Yu; Weichu (Jingzhou,
CN), Zhang; Ying (Jingzhou, CN), Li;
Rui (Jingzhou, CN), Zhao; Hui (Wuhan,
CN), Zhang; Lei (Wuhan, CN), Xia;
Wenjie (Tianjin, CN), Fan; Pingtian (Yanan,
CN), Wu; Baocheng (Karamay, CN), Shu;
Wenming (Jingzhou, CN), Ding; Fei (Qingdao,
CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
YANGTZE UNIVERSITY
Jingzhou Modern Petroleum Technology Development Co. LTD |
Jingzhou
Jingzhou |
N/A
N/A |
CN
CN |
|
|
Assignee: |
YANGTZE UNIVERSITY (Jingzhou,
CN)
JINGZHOU MODERN PETROLEUM TECHNOLOGY DEVELOPMENT CO. LTD
(Jingzhou, CN)
|
Family
ID: |
1000006484923 |
Appl.
No.: |
16/952,704 |
Filed: |
November 19, 2020 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20220127942 A1 |
Apr 28, 2022 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 23, 2020 [CN] |
|
|
202011143302.6 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B
49/00 (20130101); E21B 43/267 (20130101); E21B
33/138 (20130101) |
Current International
Class: |
E21B
43/20 (20060101); E21B 43/267 (20060101); E21B
33/138 (20060101); E21B 49/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Thompson; Kenneth L
Attorney, Agent or Firm: WPAT, PC
Claims
What is claimed is:
1. A volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously includes the following steps: S1
obtaining a plurality of reservoir parameters of Ma a target
interval of an implementation well to determine the target interval
for temporary plugging and steering fracturing, fracturing
parameters, and pumping and injection construction procedures,
wherein the fracturing parameters include at least flow rate, and
the flow rate is not less than 6 m.sup.3/min; S2 in accordance with
the pumping and injection construction procedures, pumping prefluid
and sand-carrying fluid into the target interval, and at the same
time, injecting biological oil displacement agent into the target
interval in sequence; S3 pumping temporary plugging agent into the
target interval according to the pumping and injection construction
procedures to implement crack plugging diverting; S4 pumping the
sand-carrying liquid into the target interval in accordance with
the pumping and injection construction procedures, and at the same
time injecting the biological oil displacement agent into the
target interval, wherein the sand ratio of the sand-carrying liquid
is not more than 15%; S5 pumping displacement fluid into the target
interval in accordance with the pumping and injection construction
procedures to complete the fracturing construction.
2. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 1, wherein the
prefluid is slick water fracturing fluid, and the slick water
fracturing fluid is used to create fractures and slug the reservoir
in the initial stage of fracturing, the sand carrying fluid is
slick water fracturing fluid containing proppants, the displacement
fluid is slick water fracturing fluid that does not contain
proppants.
3. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 2, wherein the
viscosity of the slick water fracturing fluid is 1.0-3.0 mPas.
4. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 1, wherein the
temporary plugging agent is MP-1 type water-soluble temporary
plugging agent for fracturing.
5. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 1, wherein after
the step 5, it also includes the following steps: S6 closing the
implementation well.
6. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 5, wherein a
boreholes closing time lasts for 15-20 days.
7. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 1, in the step S2,
the injection volume of the prefluid accounts for 30% to 50% of the
total injection volume of the fracturing fluid.
8. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 1, wherein the
step S2 includes the following steps: injecting the prefluid into
the target interval, after injecting 150-180 m.sup.3 prefluid,
beginning to alternately add 40/70 mesh quartz sand to slug, the
sand ratio starts from 2% and increases by 1% sequentially to 7%;
alternately injecting the sand-carrying liquid into the target
interval, the sand ratio of the sand-carrying liquid is increased
in three steps in multiple injections, among which the quartz sand
is 40/70 mesh; alternately injecting the sand-carrying liquid into
the target interval, the sand ratio of the sand-carrying liquid is
increased in four steps in multiple injections, among which the
quartz sand is 20/40 mesh.
9. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 8, wherein the
40/70 mesh quartz sand is injected into the sand-carrying liquid
for three times, in which the sand ratio of the sand-carrying
liquid injected for the first time is increased in three steps of
6%-7%-8%; the sand ratio of the sand-carrying liquid increases in
three steps of 7%-8%-9%; the sand ratio of the sand-carrying liquid
injected for the third time increases in three steps of
8%-9%-10%.
10. The volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously according to claim 8, wherein the
20/40 mesh quartz sand is injected into the sand-carrying liquid
for three times, wherein the sand ratio of the sand-carrying liquid
injected for the first time is increased in four steps of
6%-7%-8%-9%; the sand ratio of the sand-carrying liquid injected
for the second time is increased in four steps of 7%-8%-9%-10%; the
sand ratio of the sand-carrying liquid injected for the third time
is increased in four steps of 8%-9%-10%-11%.
Description
FIELD OF THE DISCLOSURE
The disclosure relates to volumetric fracturing method of
temporarily plugging and diverting through functional slick water
with oil displacement agent injected simultaneously.
BACKGROUND
Low-permeability oil and gas reservoirs have complex geological
conditions and poor stimulation and improvement effects. At
present, low-permeability oil and gas reservoirs are developed
through horizontal well drilling and hydraulic fracturing
technologies to increase the contact area between fractures and
reservoirs to develop low permeability reservoirs economically and
efficiently. In order to improve the fracturing effect of
low-permeability reservoirs, more advanced technologies are
required to cooperate with hydraulic fracturing to further improve
oil and gas recovery. Technical means such as multi-fracture staged
fracturing, fracturing and integration of enhanced oil recovery has
become the focus of exploration and development worldwide. Whether
it is conventional vertical well reconstruction fracturing or
multi-fracture staged fracturing in unconventional horizontal well
sections, temporary plugging agents are used for fracturing
diverting, so that the new fractures generated by fracturing fluids
are different from the previous artificial or natural fractures.
The newly opened fractures are redirected to unreformed areas or
areas that are not fully reformed, so as to establish new oil and
gas seepage channels and change the rule of oil and gas reservoir
fluid seepage and displacement, and obtain the effective reformed
volume of single well to improve the effect of low permeability
reservoirs stimulation.
The conventional enhanced oil recovery technologies include:
chemical flooding, gas flooding, thermal flooding, microbial
flooding, molecular film flooding, etc. The microbial flooding
enhanced oil recovery technology has the advantages of low cost,
convenient construction, wide application range, no damage to the
formation and construction equipment, no pollution to the
environment and so on. The conventional microbial enhanced oil
recovery construction methods mainly include: single well huff and
puff, microbial water flooding, microbial cycle flooding, microbial
water fracturing, and microbial and other oil recovery measures,
such as polymer flooding, ternary combined flooding, surfactants,
etc.
At present, diverting fracturing and enhanced oil recovery are
carried out separately as two constructions to improve oil
recovery. Generally, diverting fracturing is implemented first,
followed by enhanced oil recovery. The construction period is long,
the input process is complicated with material wasted and
environmental pollution. Situations such as incomplete removal of
temporary plugging agent and water locking effect of fracturing
fluid caused by diverting fracturing will affect the depth and
breadth of subsequent bio-displacement agent injection, affect the
oil displacement effect, and reduce the recovery of enhanced oil
recovery in the reservoir. At the same time, fractures generated by
diverting fracturing which uses high-sand ratio fracturing fluids
are less complex than conventional hydraulic fracturing, and the
affected volume is small. The volume of connected oil and gas
reservoirs is limited, which lead to the problems such as low
initial production after fracturing, rapid production decline, and
short stable production period and so on.
SUMMARY
A technical problem to be solved by the disclosure is to provide a
fracturing method that can improve construction efficiency, enhance
the injection depth and breadth of biological oil displacement
agent, enhance oil displacement effect, increase the recovery rate
of enhanced oil recovery, and increase the production of single
well.
A volumetric fracturing method of temporarily plugging and
diverting through functional slick water with oil displacement
agent injected simultaneously includes the following steps:
S1 obtaining the reservoir parameters of the target interval of an
implementation well to determine the target interval for temporary
plugging and steering fracturing, fracturing parameters, and
pumping and injection construction procedures, wherein the
fracturing parameters include at least flow rate, and the flow rate
is not less than 6 m.sup.3/min;
S2 in accordance with the pumping and injection construction
procedures, pumping the prefluid and the sand-carrying fluid into
the target interval in sequence, and at the same time, injecting
the biological oil displacement agent into the target interval;
S3 pumping temporary plugging agent into the target layer according
to the pumping and injection construction procedures to implement
crack plugging diverting;
S4 pumping the sand-carrying liquid into the target interval in
accordance with the pumping and injection construction procedures,
and at the same time injecting the biological oil displacement
agent into the target interval, wherein the sand ratio of the
sand-carrying liquid is not more than 15%;
S5 pumping displacement fluid into the target interval in
accordance with the pumping and injection construction procedures
to complete the fracturing construction.
The beneficial effect of the technical scheme proposed in this
disclosure is: by injecting oil displacement agent to reservoir,
the temporary plugging diverting fracturing is integrated with
enhanced oil recovery, which not only improves the injection depth
and breadth of biological oil displacement agent, communicates
remaining oil areas, and realizes the effect of enhanced oil
recovery and improve the single well production, as well as reduces
the construction risk of diverting fracturing, reduces construction
investment, and improves construction efficiency. At the same time,
it can overcome the incomplete removal of temporary plugging agent
and the water lock effect of fracturing fluid caused by diverting
fracturing. Meanwhile, through the use of high flow rate, low sand
ratio fracturing, the complexity of the fracture network can be
greatly increased, the sweep volume of the fractures can be
increased, and the diverting fracturing effect can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
Accompanying drawings are for providing further understanding of
embodiments of the disclosure. The drawings form a part of the
disclosure and are for illustrating the principle of the
embodiments of the disclosure along with the literal description.
Apparently, the drawings in the description below are merely some
embodiments of the disclosure, a person skilled in the art can
obtain other drawings according to these drawings without creative
efforts. In the figures:
FIG. 1 is a schematic flow diagram of an embodiment of volumetric
fracturing method of temporarily plugging and diverting through
functional slick water with oil displacement agent injected
simultaneously;
FIG. 2 is a fracture morphology diagram output by a preferred
embodiment of volumetric fracturing method of temporarily plugging
and diverting through functional slick water with oil displacement
agent injected simultaneously;
FIG. 3 is a diagram of fracturing operation and borehole pressure
curve of a preferred embodiment of a preferred embodiment of
volumetric fracturing method of temporarily plugging and diverting
through functional slick water with oil displacement agent injected
simultaneously.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Embodiment is provided below to further explain the method provided
by this disclosure.
In order to verify the feasibility of this disclosure, an
evaluation well in the Baiyinchagan Sag of the Ordos Basin was
selected as the implementation well. The fracturing design and
construction of this implementation well are designed and
constructed using volumetric fracturing method of temporarily
plugging and diverting through functional slick water with oil
displacement agent injected simultaneously provided by this
disclosure. As revealed in FIG. 1, the volumetric fracturing method
of temporarily plugging and diverting through functional slick
water with oil displacement agent injected simultaneously includes
the following steps:
S1 obtaining the reservoir parameters of the target interval of an
implementation well to determine the target interval for temporary
plugging and steering fracturing, fracturing parameters, and
pumping and injection construction procedures, wherein the
fracturing parameters include at least flow rate, and the flow rate
is not less than 6 m.sup.3/min, which has a larger flow rate than
conventional hydraulic fracturing, so as to improve the fracturing
effect of the fracturing fluid;
The target interval where temporary plugging and fracturing can be
implemented is mainly determined according to the re-construction
conditions, the mining margin and the output cost.
The pump injection construction program usually requires the use of
fracturing design software. In this embodiment, the fracturing
design software is Fracpro PT, and the pump injection program table
is set according to a large liquid volume, high flow rate, low sand
ratio, slick water volumetric fracturing method.
S2 in accordance with the pumping and injection construction
procedures, pumping the prefluid and the sand-carrying fluid into
the target interval, and at the same time, injecting the biological
oil displacement agent into the target interval in sequence,
wherein the injection volume of the prefluid accounts for 30% to
50% of the total injection volume of the fracturing fluid, which
has a larger proportion of the prefluid compared with conventional
hydraulic fracturing to improve the fracturing fluid
fracture-making ability;
S3 pumping temporary plugging agent into the target layer according
to the pumping and injection construction procedures to implement
crack plugging diverting;
S4 pumping the sand-carrying liquid into the target interval in
accordance with the pumping and injection construction procedures,
and at the same time injecting the biological oil displacement
agent into the target interval, wherein the sand ratio of the
sand-carrying liquid is not more than 15%;
S5 pumping displacement fluid into the target interval in
accordance with the pumping and injection construction procedures
to complete the fracturing construction.
S6 closing borehole on the implementation wells. In a preferred
embodiment, the boreholes closing time lasts for 15-20 days. After
that, the routine operations are completed by measuring the
pressure drop, controlling the blowout, thoroughly backwashing the
well, pulling out the fracturing string, and exploring the sand
surface of the tubing, which will not be repeated here.
The principle of the volumetric fracturing method of temporarily
plugging and diverting through functional slick water with oil
displacement agent injected simultaneously provided by this
disclosure is as follows: by adopting large liquid volume, high
flow rate, large prefluid, low sand ratio, low viscosity,
intermittent columnar stepped sanding process and injection of
biological oil displacement agent, and using high-efficiency
temporary plugging agent for fracturing diverting, namely the new
concept and new technology of oil displacement agent slick water
temporary plugging and diverting to volumetric fracturing simple
on-site implementation and relatively low cost, not only
compensates for pressure and fluid deficit caused by production,
supplements formation energy in low-pressure layers, but also
penetrates fracturing fluid to connect new reservoirs, effectively
increasing the contact area between fracturing fluid and the
reservoir and the volume of reservoir reconstruction, reducing the
oil-water interfacial tension and crude oil viscosity, and
achieving the purpose of temporary plugging and diverting to
increase production.
Preferably, the prefluid is slick water fracturing fluid, and the
slick water fracturing fluid is used to create fractures and slug
the reservoir in the initial stage of fracturing.
Preferably, the sand carrying fluid is slick water fracturing fluid
containing proppants.
Preferably, the displacement fluid is slick water fracturing fluid
that does not contain proppants.
Preferably, the viscosity of the slick water fracturing fluid is
1.0-3.0 mPas.
Preferably, the biological oil displacement agent is HE-BIO
biological oil displacement agent.
Preferably, the temporary plugging agent is MP-1 type water-soluble
temporary plugging agent for fracturing.
The above-mentioned slick water fracturing fluid, HE-BIO biological
oil displacement agent and MP-1 type water-soluble temporary
plugging agent for fracturing are all patented products of Jingzhou
Modern Petroleum Technology Development Co., Ltd.
In this example, the completion depth is 1635.0 m, the completion
zone is in the Arshan Formation, the artificial bottom hole is
1615.5 m, the joint is 4.52 m, the maximum well deviation is
3.6.degree./148.5.degree.1411.70 m, and the formation temperature
is 49.degree. C. (estimated). The formation pressure is 16 MPa
(estimated), the porosity is 5.6%, the oil saturation is 2.8%, and
the permeability is 0.16.times.10.sup.-3 um.sup.2. By comprehensive
interpretation of the dry glutenite layer, the well's logging and
logging data and related geological data of this well, and the
evaluation and analysis of the stratum, it is believed that the
foundation of this layer is poor, the effect after compaction is
difficult to guarantee, and there is a great geological risk. The
specific process plan is:
(1) Adopt the fracturing method of stratification sealing and
combined layer fracturing;
(2) The use of large liquid volume, high flow rate, low sand ratio,
and large prefluid temporary plugging and diverting to volumetric
fracturing, which can not only increase the reconstruction volume,
but also supplement the formation energy;
(3) Small particle size and variable particle size proppants are
used to meet the filling and support of complex multi-stage
fractures;
(4) Using 12% dilute hydrochloric acid to clear the perforation
blockage, dredge the perforation holes, remove the pollution near
the well, and reduce the hole resistance and rupture pressure;
(5) Adopting fracturing--temporary plugging and
diverting--fracturing--closing--draining--oil production
construction technology to achieve the best fracturing and oil
displacement effect. The well is closed for 15 to 20 days after
fracturing, which further improves the effect of fracturing.
In this example, a fractured well section of 1562.4 to 1585.0 m is
selected as the target interval for temporary plugging and
diverting fracturing. Specifically, hydraulic sandblasting
perforation with the same diameter is used, and the perforation
effectively penetrates the casing and cement ring of the formation,
the perforation penetration depth reaches more than 400 mm, and the
perforation avoids the casing coupling.
In this example, the simulation parameter table of the fracturing
design software Fracpro PT is shown in Table 1, the pump injection
program table is shown in Table 2, and the fracture morphology
simulated by the fracturing design software Fracpro PT is shown in
FIG. 2:
TABLE-US-00001 TABLE 1 Software simulation fracture parameter table
Designed seam length (m) 175 Flow rate (m.sup.3/min) 6 Pre-fluid
volume (m.sup.3) 13 Total volume of prefluid 525 (m.sup.3) Total
volume of sand-carrying 739 Total volume of proppant 40.2 liquid
(m.sup.3) (m.sup.3) Temporary plugging agent 300 Biological oil
displace- 2.0 (20-120 mesh) (Kg) ment agent (m.sup.3) Displacement
fluid volume 40 Average total crack 15.1 (m.sup.3) height (m)
Maximum width of cracks at 0.68 Crack height at the shaft 40.5
shaft wall (cm) wall (m)
TABLE-US-00002 TABLE 2 Pumping and injection construction
procedures table Liquid Sand Sand Oil Construction volume ratio
volume Proppant displacement No. stage Fluid name (m.sup.3) (%)
(m.sup.3) type agent 1 Fill the shaft Slick water 5 0 0 2 Squeeze
acid 12% HCl 8 0 0 to clear holes 3 First stage of Pre-fluid 365
2%-3% 5.85 40/70 0.5% in the main -4%-5% mesh first 100 m.sup.3
fracturing -6%-7% quartz of the first sand stage 4 Second stage
Sand 59 6%-7% 1.82 40/70 of main carrying -8% mesh fracturing
liquid quartz sand 5 62 7%-8% 2.09 40/70 -9% mesh quartz sand 6 67
8%-9% 2.36 40/70 -10% mesh quartz sand 7 Third stage 67 6%-7% 2.27
20/40 of main -8%-9% mesh fracturing quartz sand 8 65 7%-8% 2.45
20/40 0.5% in the -9%-10% mesh last 100 m.sup.3 quartz of the third
sand stage 9 63 8%-9% 2.57 20/40 -10%-11% mesh quartz sand 10
Temporarily Slick water 5 0 0 20-120 plugging and mesh diverting
temporary plugging agent 300 Kg 11 Fourth stage Sand 68 7%-9% 2.62
20/40 0.5% in the of main carrying -11%-13% mesh first 100 m.sup.3
fracturing liquid quartz of the fourth sand stage 12 72 8%-9% 2.96
20/40 -10%-12% mesh quartz sand 13 77 9%-10% 3.28 20/40 -11%-13%
mesh quartz sand 14 87 10%-11% 4.72 20/40 0.5% in the -12%-14% mesh
last 100 m.sup.3 quartz of the first sand stage 15 52 12%-13% 34.37
20/40 -14%-15% mesh -16%-8% quartz sand 16 Displacement
Displacement 40 0 0 liquid 17 Total 1317 40.2
In this embodiment, as revealed in Table 2, step S2 is performed in
three stages, and the specific steps include:
The first stage: injecting the prefluid into the target interval,
after injecting 150-180 m.sup.3 prefluid, beginning to alternately
add 40/70 mesh quartz sand to slug, the sand ratio starts from 2%
and increases by 1% sequentially to 7%. Preferably, the bio-oil
displacement agent is injected at a rate of 0.5% at the same time
as the first 100 m.sup.3 of prefluid in the first stage is
injected.
The second stage: alternately injecting the sand-carrying liquid
into the target interval. The sand ratio of the sand-carrying
liquid is increased in three steps in multiple injections, among
which the quartz sand is 40/70 mesh. Preferably, the 40/70 mesh
quartz sand is injected into the sand-carrying liquid for three
times, in which the sand ratio of the sand-carrying liquid injected
for the first time is increased in three steps of 6%-7%-8%; The
sand ratio of the sand-carrying liquid increases in three steps of
7%-8%-9%; the sand ratio of the sand-carrying liquid injected for
the third time increases in three steps of 8%-9%-10%.
The third stage: alternately injecting the sand-carrying liquid
into the target interval. The sand ratio of the sand-carrying
liquid is increased in four steps in multiple injections, among
which the quartz sand is 20/40 mesh. Preferably, the 20/40 mesh
quartz sand is injected into the sand-carrying liquid for three
times, wherein the sand ratio of the sand-carrying liquid injected
for the first time is increased in four steps of 6%-7%-8%-9%; the
sand ratio of the sand-carrying liquid injected for the second time
is increased in four steps of 7%-8%-9%-10%; the sand ratio of the
sand-carrying liquid injected for the third time is increased in
four steps of 8%-9%-10%-11%. In the third stage, the last 100
m.sup.3 of the sand-carrying liquid was injected while the
bio-displacement agent is injected at a rate of 0.5%.
Preferably, before step S2, the wellbore should be filled with 5
m.sup.3 slick water fracturing fluid at a flow rate of 0.5
m.sup.3/min, and then removed with 8 m.sup.312% dilute hydrochloric
acid at a flow rate of 0.5-1 m.sup.3/min to clear the perforation,
the pollution near the well is removed, and the perforation
resistance and rupture pressure are reduced.
The first stage of the step S2 is mainly to further expand the
micro-fracture system that has been formed in the pre-fluid
fracturing and add small particle size proppant (40/70 mesh quartz
sand) to achieve as much as possible to various small-scale
micro-fracture systems, as well as to eliminate the perforations
and friction near the well, and communicate and saturate the
natural fractures near the well. In the second and third stages,
the high flow rate slick water fracturing fluid generates the net
pressure required to meet the fracture half-length and the fracture
width to continue to expand, completely open the main fractures of
the remote well and connect the secondary fractures and the
micro-natural, while in the third stage, large-size proppant (20/40
mesh quartz sand) is selected at the same time to support the
gradually expanding fracture system.
In this embodiment, as revealed in Table 2. The specific steps of
step S3 include: injecting 300 Kg of temporary plugging agent
powder into the target interval, and the temporary plugging agent
is directly injected into the sand mixing tank. Preferably, the
temporary plugging agent adopts a 20-120 mesh MP-1 type
water-soluble temporary plugging agent for fracturing, so as to
realize the temporary plugging and turning in the fracture, create
branch fractures and micro-fractures and pass through the
inter-fracture interference of multiple fractures to further
increase the fractures complexity.
In this embodiment, as revealed in Table 2, the specific steps of
step S4 include: alternately injecting a sand-carrying liquid
containing 20/40 mesh quartz sand into the target interval, and the
sand ratio of the sand-carrying liquid is increased for four or six
steps, and the injection is divided into multiple times.
Preferably, the sand ratio of the sand-carrying liquid injected for
the first time is increased in four steps of 7%-9%-11%-13%; the
sand ratio of the sand-carrying liquid injected for the second time
is increased in four steps of 8%-9%-10%-12%; the sand ratio of the
sand-carrying liquid injected for the third time is increased in
four steps of 9%-10%-11%-13%, the sand ratio of the sand-carrying
liquid injected for the fourth time is increased in four steps of
10%-11%-12%-14%, and the sand ratio of the sand-carrying liquid
injected for the fifth time is increased in six steps of
12%-13%-14%-15%-16%-8% until all proppant injection is
completed.
After the sand-carrying fluid injection is completed, 40 m.sup.3 of
displacement fluid is injected into the target interval to complete
all the main fracturing operations.
Preferably, during the first 100 m.sup.3 and the last 100 m.sup.3
of the fourth stage, the bio-oil displacement agent is injected at
a rate of 0.5% while the sand-carrying liquid is injected.
After completing the temporary plugging and diverting, continuing
to use the large liquid volume and multi-step sand ratio alternate
fracturing mode to continue to propagate the fractures after the
diverting, and realize the support of the fractures and fractures,
and finally form a complex network of volumetric fractures, so as
to achieve larger reservoir reconstruction volume, while expanding
the bio-displacement agent to all fractures, effectively reducing
oil-water surface tension and crude oil viscosity, and has a good
cleaning effect on oil sands. In the process of well closing,
HE-BIO Biological oil displacement agents can generate carbon
dioxide in situ in the oil reservoir to further improve the oil
displacement effect.
Preferably, during the first 100 m.sup.3 and the last 100 m.sup.3
of the fourth stage, the bio-oil displacement agent is injected at
a rate of 0.5% while the sand-carrying liquid is injected.
After completing the temporary plugging and diverting, continue to
use the large liquid volume and multi-step sand ratio alternate
fracturing mode to continue to propagate the fractures after the
turning, and realize the support of the fractures and fractures,
and finally form a complex network of volumetric fractures. Larger
reservoir reconstruction volume, while expanding the
bio-displacement agent to all fractures, effectively reducing
oil-water surface tension and crude oil viscosity, and has a good
cleaning effect on oil sands. In the process of boring wells,
HE-BIO Biological oil displacement agents can generate carbon
dioxide in situ in the oil reservoir to further improve the oil
displacement effect.
Completed the fracturing construction of the implementation well
according to the pumping and injection construction procedures, and
the construction was smooth; the injection of clearing acid before
fracturing can achieve the purpose of dredging the blasthole and
connecting the formation, reducing the construction friction and
ensuring the normal progress of subsequent construction; By
injecting low-viscosity slick water fracturing fluid with high flow
rate, multi-fractures and multi-network fractures are formed, which
increases the reconstruction volume, and uses different particle
size proppants to achieve effective filling of multi-stage
fractures. The post-compression G-function analysis shows (in FIG.
3) that the goal of fracture complication is achieved. The net
pressure is 11.81 MPa, which is beneficial to overcome the
horizontal two-way stress difference and realize the crack turning.
The fitted reservoir pressure increased by 5.07 MPa compared with
the original pressure, indicating that the large liquid injection
played a role in energy storage. Even though the wellhead pressure
drops to zero during flowback after pressure, liquid can still be
discharged, indicating that the liquid supply capacity has been
greatly improved.
In summary, the beneficial effects of this disclosure are as
follows:
(1) by injecting oil displacement agent to reservoir, the temporary
plugging diverting fracturing is integrated with enhanced oil
recovery, which not only improves the injection depth and breadth
of biological oil displacement agent, communicates remaining oil
areas, and realizes the effect of enhanced oil recovery and
improves the single well production, as well as reduces the
construction risk of diverting fracturing, reduces construction
investment, and improves construction efficiency. At the same time,
it can overcome the incomplete removal of temporary plugging agent
and the water lock effect of fracturing fluid caused by diverting
fracturing.
(2) through the integrated effect of large liquid volume, high flow
rate, low sand ratio, intermittent columnar multi-step sanding
process and the injected biological oil displacement agent, it not
only compensates for the pressure and fluid deficit caused by
production, but also supplements the formation energy of the
low-pressure layer, and the liquid breaks down and contacts the new
reservoir, which effectively increases the contact area with the
reservoir and the reforming volume of the reservoir, and reduces
the oil-water interfacial tension, achieving the purpose of
increasing production by temporary plugging and diverting
volumetric fracturing.
It is to be understood, however, that even though numerous
characteristics and advantages of this disclosure have been set
forth in the foregoing description, the disclosure is illustrative
only, and changes may be made in detail, especially in matters of
shape, size, and arrangement of parts within the principles of this
disclosure to the full extent indicated by the broad general
meaning of the terms in which the appended claims are
expressed.
* * * * *